The two terms are usually used interchangeably. It's a progressive chronic pain condition that usually shows up after an injury (even the most mild) and usually affects limbs. The most characteristic symptom is burning, unrelenting pain in the area(s) effected, along with swelling, sensitivity to touch, and excessive sweating. CRPS/RSD is divided into two types - type 1 has no nerve injury and type 2 does have nerve injury.

Since there's currently no known cure for the disease, people who have it most often struggle to maintain their function and manage their pain, so they can live as close to a normal life as possible.